-
Non-Supercell Tornadoes and the NST Parameter: Landspout
Tornadoes June 16 2004WFO La Crosse Research Series #11
Kenneth R. Cook, Dan Baumgardt, Todd SheaKenneth R. Cook, Dan
Baumgardt, Todd SheaNOAA/National Weather Service La Crosse,
WINOAA/National Weather Service La Crosse, WI
The views expressed are those of the authors and do not
necessarThe views expressed are those of the authors and do not
necessarily represent those of the National Weather Service.ily
represent those of the National Weather Service.
-
ObjectiveObjective
Improve operational forecasts of nonsupercell Improve
operational forecasts of nonsupercell tornadogenesis (NST) by
increasing situational tornadogenesis (NST) by increasing
situational awareness of:awareness of:
their behavior.their behavior.their mesotheir meso-- and
misoscale (40mand misoscale (40m--4km) environment.4km)
environment.
How successful can a warning program be for How successful can a
warning program be for NST? NST?
At least 6 of our 18 tornadoes in 2004 were NST.At least 6 of
our 18 tornadoes in 2004 were NST.
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OutlineOutline
Literature Review of NSTLiterature Review of NSTReview 16 June
2004 NST caseReview 16 June 2004 NST caseSituational Awareness for
NST EventsSituational Awareness for NST Events
The NST ParameterThe NST ParameterThe ESP ParameterThe ESP
Parameter
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Literature ReviewLiterature Review
1978: discussion begins on a land mode of 1978: discussion
begins on a land mode of tornadogenesis where mesocyclones are not
present. tornadogenesis where mesocyclones are not present. Cooley,
1978 Cooley, 1978 ColdCold--Air FunnelsAir Funnels
No indications of radar signatures which have a high No
indications of radar signatures which have a high correlation of
severe weather (e.g., hooks, vcorrelation of severe weather (e.g.,
hooks, v--notches, notches, echoecho--free vaults). No free
vaults). No indication of rotation in the storm indication of
rotation in the storm cellscells. .
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Literature ReviewLiterature Review
Burgess and Donaldson, 1979Burgess and Donaldson, 1979Several
weak tornadoes with Several weak tornadoes with no no
mesocyclone.mesocyclone.All All occurred during the occurred during
the developmental stagesdevelopmental stages of the of the storms.
storms. One tornado formed five One tornado formed five minutes
prior to first echo.minutes prior to first echo.
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Literature ReviewLiterature Review
Bluestein, 1985Bluestein, 1985LandspoutLandspout term
introduced.term introduced.Form within 30 min. of first radar
echo.Form within 30 min. of first radar echo.Parent storm was not a
supercell and no Parent storm was not a supercell and no
mesocyclone signatures were detected by mesocyclone signatures were
detected by radar.radar.Similar to waterspout formation where
Similar to waterspout formation where local vertical vorticity
stretching is the local vertical vorticity stretching is the
sourcesource of the vortex at intersecting of the vortex at
intersecting outflows.outflows.
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Literature ReviewLiterature Review
Wakimoto and Wilson, 1989 (WW89)Wakimoto and Wilson, 1989
(WW89)Inspected 27 visual vortices associated with nonInspected 27
visual vortices associated with non--supercell supercell storms in
the CINDE field project:storms in the CINDE field project:
Tornadoes formed during the updraft stage of rapidly developing
Tornadoes formed during the updraft stage of rapidly developing
storms.storms.The vorticity source for the tornadoes originated at
lowThe vorticity source for the tornadoes originated at low--levels
as small levels as small vorticies produced by shearing instability
along a convergence vorticies produced by shearing instability
along a convergence boundary and is then stretched by updrafts.
boundary and is then stretched by updrafts.
Environment:Environment:
\\
Boundaries having strong horizontal shears, possessing
wavelikeBoundaries having strong horizontal shears, possessing
wavelikeinflections indicative of 1inflections indicative of 1--3km
vertical vorticity circulations 3km vertical vorticity circulations
(misocyclones) with rapidly developing storms above. (misocyclones)
with rapidly developing storms above.
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Literature ReviewLiterature ReviewBrady and Szoke, 1989
(BS89):Brady and Szoke, 1989 (BS89):
Analysis of 26 July 1985 Erie, CO tornado. Analysis of 26 July
1985 Erie, CO tornado. Similar findings to WW89. Similar findings
to WW89. Misocyclones (
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Literature ReviewLiterature Review
Roberts and Wilson, 1995:Roberts and Wilson,
1995:DualDual--Doppler analyses of three F2Doppler analyses of
three F2--F3 tornadoes 15 June 1988 in F3 tornadoes 15 June 1988 in
Denver. Found to be NST originating from misocyclone vertical
Denver. Found to be NST originating from misocyclone vertical
growthgrowthnot midnot mid--level mesocyclone. level mesocyclone.
Confirmed many findings found in WW89 and BS89. Confirmed many
findings found in WW89 and BS89. Storms displayed supercell traits
after NST (e.g., WER, BWER).Storms displayed supercell traits after
NST (e.g., WER, BWER).
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Literature ReviewLiterature Review
Lee and Wilhelmson (1997, I):Lee and Wilhelmson (1997,
I):Investigated misocyclone development using a Investigated
misocyclone development using a drydry, high , high resolution, 3d
numerical simulation independent of moist resolution, 3d numerical
simulation independent of moist processes.processes.Used a
simulated outflow (Used a simulated outflow (--3K cooler) with
southerly ambient 3K cooler) with southerly ambient flow ahead.
flow ahead.
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Literature ReviewLiterature Review
Lee and Wilhelmson (1997, I):Lee and Wilhelmson (1997,
I):Simulations verified misocyclones exist.Simulations verified
misocyclones exist.Theorized misocycloneTheorized
misocyclone--induced updrafts may induced updrafts may have
significantly contributed to convection have significantly
contributed to convection initiation.initiation.Lobe and cleft
response.Lobe and cleft response.Upscale consolidation of smaller
misocyclones. Upscale consolidation of smaller misocyclones.
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Literature ReviewLiterature Review
Lee and Wilhelmson (1997, I):Lee and Wilhelmson (1997,
I):Traveling misocyclones along Traveling misocyclones along the
boundary in the direction the boundary in the direction of the
preof the pre--boundary mean boundary mean wind.
Consolidation.wind. Consolidation.33--D conceptual model of D
conceptual model of misocyclone development misocyclone development
along the boundary. along the boundary.
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Literature ReviewLiterature Review
Lee and Wilhelmson (1997, II):Lee and Wilhelmson (1997,
II):Simulations as in Part I but Simulations as in Part I but with
moist processes. with moist processes. Confirmed:Confirmed:
Shearing instability creates Shearing instability creates
misocyclones.misocyclones.Tornadic origin near the surface.Tornadic
origin near the surface.Vertical vorticity stretching is Vertical
vorticity stretching is primary source of vortex primary source of
vortex intensifications. intensifications.
Misocyclones influence the Misocyclones influence the pattern of
convective forcing pattern of convective forcing along a boundary.
along a boundary.
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Literature ReviewLiterature Review
Lee and Wilhelmson (1997, II):Lee and Wilhelmson (1997, II):For
a vortex sheet that breaks For a vortex sheet that breaks down into
a number of vortices down into a number of vortices (later
misocyclones) in (later misocyclones) in conjunction with known
conjunction with known favorable environmental favorable
environmental conditions for convective conditions for convective
development, development, one can expect not one can expect not
just one but a number of just one but a number of tornadoes that
occur tornadoes that occur concurrently along a common concurrently
along a common boundary.boundary. A family of A family of
tornadoes.tornadoes.New storm outflow influences New storm outflow
influences NST timing and intensity (25%+ NST timing and intensity
(25%+ delV).delV).
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Literature ReviewLiterature Review
Lee and Wilhelmson (2000, III):Lee and Wilhelmson (2000,
III):Continued numerical simulations Continued numerical
simulations with altered environments.with altered environments.As
CAPE increased, NST vortex As CAPE increased, NST vortex strength
increased, vertical strength increased, vertical vorticity was
stretched in shorter vorticity was stretched in shorter time
periods.time periods.1010--20 kts of change in the line 20 kts of
change in the line parallel wind field needed. parallel wind field
needed. Otherwise, NST less likely.Otherwise, NST less likely.The
nearThe near--surface southerly winds surface southerly winds
correlated to misocyclone correlated to misocyclone strength and
progression along strength and progression along the boundary. the
boundary.
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Literature ReviewLiterature Review
Davies (2002, website):Davies (2002, website):Environments
supportive of Environments supportive of NST:NST:
A slowA slow--moving or stationary moving or stationary wind
shift boundary with wind shift boundary with pockets of vertical
vorticity pockets of vertical vorticity Steep lapse rates (
>9C/km) in Steep lapse rates ( >9C/km) in the lowest 1 to 2
km the lowest 1 to 2 km LFC heights that are relatively LFC heights
that are relatively low (around 2200 m AGL or low (around 2200 m
AGL or lower) and very close above the lower) and very close above
the LCL height, with little CIN LCL height, with little CIN between
the two levels.between the two levels.Little CIN. Little CIN.
Jon M. Davies Web Site: Jon M. Davies Web Site:
http://members.cox.net/jondavies1/tornado_fcsting/nonsprcll_torshttp://members.cox.net/jondavies1/tornado_fcsting/nonsprcll_tors.htm.htm
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Literature Review SummaryLiterature Review Summary
Environments supportive of NST:Environments supportive of
NST:Convergent surface boundary with 10Convergent surface boundary
with 10--20 kts of line20 kts of line--parallel shear across it.
parallel shear across it. Misocyclones, slowMisocyclones,
slow--moving? moving? Larger 0Larger 0--3km MLCAPE (>150 J/Kg),
3km MLCAPE (>150 J/Kg), larger MUCAPE. larger MUCAPE. Steep
subSteep sub--cloud lapse rates ( >9C/km) cloud lapse rates (
>9C/km) LFC heights that are relatively low LFC heights that are
relatively low (around 2200 m AGL or lower) and (around 2200 m AGL
or lower) and very close above the LCL heightvery close above the
LCL heightLittle CIN.Little CIN.NonNon--supercell 0supercell 0--6km
bulk wind shear. 6km bulk wind shear.
StormStorm--scale NST:scale NST:Source vorticity originates from
Source vorticity originates from misocyclones traveling along the
misocyclones traveling along the shear boundary.shear
boundary.Boundary temperature gradient of 3K Boundary temperature
gradient of 3K seems to enhance forcing. Nearby seems to enhance
forcing. Nearby outflow increases NST parent vortex outflow
increases NST parent vortex strength.strength.Radar reflectivity of
0Radar reflectivity of 0--30dbZ during 30dbZ during tornado onset.
Rapid reflectivity tornado onset. Rapid reflectivity increase in
minutes. increase in minutes. NSTNST--type tornadoes occur in type
tornadoes occur in families. If one occurs, expect more!families.
If one occurs, expect more!Storm may produce supercell Storm may
produce supercell structures further into lifecycle.structures
further into lifecycle.Downdraft usually destroys tornado.
Downdraft usually destroys tornado.
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2004 June 16: Environment2004 June 16: Environment
Weak stationary surface boundary convected at 1730Z.Weak
stationary surface boundary convected at
1730Z.ConvectivelyConvectively--enhanced deep cyclonic shortwave
enhanced deep cyclonic shortwave approaching. approaching.
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2004 June 16: Environment2004 June 16: Environment
Eta 500mb 18zEta 500mb 18z2020--25 knots25 knots
Mean cloud bearing Mean cloud bearing wind 230@20ktswind
230@20kts
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2004 June 16: Environment2004 June 16: Environment
RUC Surface MSLP RUC Surface MSLP 15,18,21z15,18,21zSurface low
center Surface low center approaching.approaching.NENE--SW surface
SW surface boundary to become boundary to become stationary over
Iowa. stationary over Iowa.
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentFirst:
echo 1730z, CFirst: echo 1730z, C--G strike 1830z, NST 1900z.G
strike 1830z, NST 1900z.
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentLaps
Surface Moisture Convergence, Wind, METARLaps Surface Moisture
Convergence, Wind, METAR
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentLaps
0Laps 0--6km Bulk Shear (kts)6km Bulk Shear (kts)
LAPS Sounding taken here
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentLaps
sounding on boundary (0Laps sounding on boundary (0--1km mean
parcel)1km mean parcel)
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentLaps
0Laps 0--3km ML CAPE3km ML CAPE
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentLaps
0Laps 0--1km Lapse Rate1km Lapse Rate
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentLaps
Surface Relative VorticityLaps Surface Relative Vorticity
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18z 18z 2004 June 16: Environment2004 June 16: EnvironmentSPC
0SPC 0--3km CAPE and Surface Relative Vorticity3km CAPE and Surface
Relative Vorticity
Resolution of RUC draws the eye to Rel Vort region NW of
Boundary.
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18z 18z 2004 June 16: Environment2004 June 16: Environment
LAPS Environmental Parameter LAPS Environmental Parameter (On
the Boundary)(On the Boundary)
18Z Value 18Z Value
00--6km Bulk Shear 6km Bulk Shear 2525--30 kts30 kts00--3km ML
CAPE3km ML CAPE 175175--200 J/Kg200 J/KgML CAPEML CAPE
15001500--1800 J/ Kg1800 J/ KgML CINML CIN 00--20 J/Kg20
J/Kg00--1km Lapse Rate1km Lapse Rate 9.5 C/Km9.5 C/KmLCL/LFC
HeightLCL/LFC Height 1000m1000mSurface Relative Vorticity (10km
grid)Surface Relative Vorticity (10km grid) 77--12 /1e12
/1e--55
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Radar Loop 1722zRadar Loop 1722z--2051z (fast)2051z (fast)
Cold pool sampled in Preston, MN (Cold pool sampled in Preston,
MN (--3 deg C).3 deg C).
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Radar Loop 1722zRadar Loop 1722z--1900z (slow)1900z (slow)NST
theory would suggest TORs upon first echoes.NST theory would
suggest TORs upon first echoes.
Boundary not sufficient for NST alone, cold pool needed.Boundary
not sufficient for NST alone, cold pool needed.
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19z 19z 2004 June 16: Environment2004 June 16:
EnvironmentIncreasing northerly flow north of boundary.Increasing
northerly flow north of boundary.
Boundary moving in
WI.
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19z 19z 2004 June 16: Environment2004 June 16: EnvironmentCold
pool strengthens southeasterly flow, relative Cold pool strengthens
southeasterly flow, relative vorticity increases along
boundary.vorticity increases along boundary.
Zoom to a developing
cell
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2004 June 16: Osage Cell 2004 June 16: Osage Cell NST occurs at
1947ZNST occurs at 1947Z
PT
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2004 June 16: Osage Cell 2004 June 16: Osage Cell
19311931--2011z 0.5 deg ref loop. Tor from 19472011z 0.5 deg ref
loop. Tor from 1947--2005z.2005z.
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2004 June 16: Osage Cell 2004 June 16: Osage Cell Tornado on
updraft/downdraft gradient, misocyclone Tornado on
updraft/downdraft gradient, misocyclone seen via proxy of cloud
rotation? seen via proxy of cloud rotation?
T
Looking east, 1955z
P
1951z 0.5 deg base Z75nmi from radar, beam ~7500 ft AGL.
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2004 June 16: Osage Cell 2004 June 16: Osage Cell TOR moves
southwest under developing updraft, vortex TOR moves southwest
under developing updraft, vortex strengthens. Precipitation on car,
TOR dissipates.strengthens. Precipitation on car, TOR
dissipates.
Looking E, then S, then SWLooking E, then S, then SW10x normal
speed10x normal speed
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2004 June 16: Osage Cell 2004 June 16: Osage Cell Misocyclone
moving southwest along boundary while Misocyclone moving southwest
along boundary while updrafts moved northeast with mean wind.
updrafts moved northeast with mean wind.
Northerly flow
Cold Pool
Looking Southeast!
Lee and Wilhelmson,
2000.
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2004 June 16: Osage Cell 2004 June 16: Osage Cell 0.5 deg base Z
and SRM (10kt delV) at peak TOR time.0.5 deg base Z and SRM (10kt
delV) at peak TOR time.
T T
75nmi from radar, center of beam ~7500 ft AGL. 75nmi from radar,
center of beam ~7500 ft AGL.
Radar Radar
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2004 June 16: Summary 2004 June 16: Summary
NSTNST--type tornadoes observed with no mesocyclones type
tornadoes observed with no mesocyclones present prior to formation.
Strongest rotation typically present prior to formation. Strongest
rotation typically around 10kts or less in radar velocity data.
around 10kts or less in radar velocity data. Environment favorable
for NST but cold pool seemed Environment favorable for NST but cold
pool seemed to be key to misocyclone enhancement. to be key to
misocyclone enhancement.
Steep 0Steep 0--1km rates, 01km rates, 0--3km MLCAPE>150
J/Kg, non3km MLCAPE>150 J/Kg, non--supercellular 0supercellular
0--6km Bulk Shear, ML CAPE >1500 J/Kg all 6km Bulk Shear, ML
CAPE >1500 J/Kg all coincident on a stationary surface
boundary.coincident on a stationary surface boundary.Ambient line
parallel wind shear not 10Ambient line parallel wind shear not
10--20 kts (LW,2000).20 kts (LW,2000).Surface relative vorticity a
diagnostic for the potential Surface relative vorticity a
diagnostic for the potential downscaling of vorticity and
misocyclone presence? downscaling of vorticity and misocyclone
presence?
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2004 June 16: Summary 2004 June 16: Summary
New storms initiated, and tornadoes moved, southwest New storms
initiated, and tornadoes moved, southwest along the boundary while
the mean wind was northeast. along the boundary while the mean wind
was northeast. This seems to coincide with misocyclone movement
This seems to coincide with misocyclone movement along the boundary
toward the southwest.along the boundary toward the southwest.
Rotated Lee and Wilhelmson (2000) conceptual model. Rotated Lee
and Wilhelmson (2000) conceptual model.
Convective cell lifecycles were 50 minutes or less with
Convective cell lifecycles were 50 minutes or less with tornadoes
occurring in the first 20 minutestornadoes occurring in the first
20 minutes. Osage . Osage tornado confirmed to occur at or before
first echo.tornado confirmed to occur at or before first
echo.Family of tornadoesFamily of tornadoes observed. All were F0
and F1 observed. All were F0 and F1 (Osage). (Osage).
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Situational AwarenessSituational AwarenessWith current radar
technology, sampling NST and nonWith current radar technology,
sampling NST and non--supercell supercell tornadoes is very limited
due to time and space scales of the phtornadoes is very limited due
to time and space scales of the phenomena. enomena. Situation
awareness of the environmental conditions that supportSituation
awareness of the environmental conditions that support NST NST are
key. are key.
Familiar with parameters discussed in this talk. Familiar with
parameters discussed in this talk. Higher resolution analysis is
favored (10km or less: LAPS). Higher resolution analysis is favored
(10km or less: LAPS). MesonetMesonet!!When environments for
misocyclones are present along a boundary,When environments for
misocyclones are present along a boundary, after one nonafter one
non--supercellular tornado occurrence, supercellular tornado
occurrence, expect more!expect more!
Focus on new updrafts expected provided the environment is
similFocus on new updrafts expected provided the environment is
similar or nearby. ar or nearby. Cold pool may enhance a boundary
for misocyclone development. Cold pool may enhance a boundary for
misocyclone development.
Not all nonsupercell tornadoes are nonNot all nonsupercell
tornadoes are non--damaging! damaging!
Lead time possible on the order of minutes. Lead time possible
on the order of minutes. ARX from negative lead times tors 1ARX
from negative lead times tors 1--3 to five minutes for tors 43 to
five minutes for tors 4--6. 6. SVS and HWO making the public
aware.SVS and HWO making the public aware.
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Situational AwarenessSituational AwarenessNST Environment
Parameter:
0-1km Lapse Rate > 9C00--3km MLCAPE > 100 J/Kg3km MLCAPE
> 100 J/KgMLCIN < 25 J/KgMLCIN < 25 J/Kg00--6km Bulk Shear
< 26kts6km Bulk Shear < 26ktsSurface Relative Vorticity >
8 /1e5sSurface Relative Vorticity > 8 /1e5s
00--1km AGL Lapse Rate 01km AGL Lapse Rate 0--3km MLCAPE (225
3km MLCAPE (225 -- MLCIN) (36 MLCIN) (36 -- BlkShrBlkShr
00--6km6km) Sfc Relative Vorticity) Sfc Relative Vorticity9 C/km
100J/Kg 9 C/km 100J/Kg 200200 5 8 /1e5s5 8 /1e5s
NST >= 1 then NST possible.NST >= 1 then NST
possible.Applying this with understanding!Applying this with
understanding!
Based on NST research you saw here.Based on NST research you saw
here.Stationary boundary (or nearly stationary) with wind shift.
Stationary boundary (or nearly stationary) with wind shift.
X XX X=
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18z 18z 2004 June 16: NST Parameter2004 June 16: NST
Parameter
NST >= 1 then NST NST >= 1 then NST possible (red,
purple). possible (red, purple). Earliest Earliest TORsTORsoccurred
here.occurred here.
False AlarmsFalse Alarms
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19Z 30 March 200519Z 30 March 2005: NST Parameter: NST
Parameter
NonNon--supercell deep supercell deep shear. shear. Stationary
boundary Stationary boundary with 0with 0--3km CAPE.3km CAPE.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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20Z 30 March 200520Z 30 March 2005: NST Parameter: NST
Parameter
NonNon--supercell deep supercell deep shear. shear. Stationary
boundary Stationary boundary with 0with 0--3km CAPE.3km CAPE.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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21Z 30 March 200521Z 30 March 2005: NST Parameter: NST
Parameter
NonNon--supercell deep supercell deep shear. shear. Stationary
boundary Stationary boundary with 0with 0--3km CAPE.3km CAPE.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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22Z 30 March 200522Z 30 March 2005: NST Parameter: NST
Parameter
Diminishing threat.Diminishing threat.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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30 March 200530 March 2005: NST Parameter: NST Parameter
15Z RUC 6hour 15Z RUC 6hour forecast valid 21Z.forecast valid
21Z.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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30 March 200530 March 2005: NST Parameter: NST Parameter
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30 March 200530 March 2005: NST Parameter: NST Parameter
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5 April 20055 April 2005: NST Parameter: NST Parameter
15Z RUC 9 hr 15Z RUC 9 hr forecast valid at 21Z. forecast valid
at 21Z. Occluded low with Occluded low with nearly stationary
nearly stationary boundary.boundary.NST threat area near NST threat
area near KDDC in afternoon.KDDC in afternoon.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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5 April 20055 April 2005: NST Parameter: NST Parameter
18Z RUC 1 hr 18Z RUC 1 hr forecast valid at 19Z. forecast valid
at 19Z. Slightly higher NST Slightly higher NST threat. threat.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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5 April 20055 April 2005: NST Parameter: NST Parameter
1933Z 0.5 deg 1933Z 0.5 deg brefbreffrom KDDC. from KDDC.
TornadoTornado
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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5 April 20055 April 2005: NST Parameter: NST Parameter
2020Z 0.5 deg 2020Z 0.5 deg brefbreffrom KDDC. from KDDC.
TornadoTornado
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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5 April 20055 April 2005: NST Parameter: NST Parameter
The only tornadoes occurred only along the max NST axis.
-
Enhanced Stretching Potential?
ESP = (LR 0-2 or 0-3 7.0) x CAPE 0-3
(Set negative values to 0; limit CAPE0-3 to 100 J kg-1)
A way to combine low-level lapse rate and low-level CAPE to
suggest increased potential for low-level stretching?
Slide courtesy Jon Davies
-
Slide courtesy Jon Davies
-
Slide courtesy Jon Davies
-
Steep low-level lapse rates intersect low-level CAPE
Slide courtesy Jon Davies
-
Slide courtesy Jon Davies
-
F2 tornadoon ground
at outflow-front intersection
Slide courtesy Jon Davies
-
nonsupercell tornadoes 00-01 UTC
Slide courtesy Jon Davies
-
314 cases with steep low-level lapse ratesnon-tornadic and
tornadic
(RUC proximity analysis soundings)
Small SRH/high LCLtornado cases
(nonsupercell?) tend toward
larger ESP values?
Slide courtesy Jon Davies
Movie here
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19 April 200519 April 2005: NST Parameter: NST Parameter
Slides courtesy Rich Slides courtesy Rich NaistatNaistat SOO
MPX. SOO MPX.
-
RUC FCST OF NST>1 (IMAGE) AND ESP FOR 21Z FROM 15Z
-
p p g
Laps 21z sfc moisture flux div (contours for boundary id)
-
21z laps image NST >1
21z laps contours are ESP values.
-
2128z mpx .5 degree reflectivity
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19 April 200519 April 2005: NST Parameter: NST Parameter
38 minute lead time 38 minute lead time on an NST tornado. on an
NST tornado. WELL North of an WELL North of an occluding low.
occluding low.
NST >= 1 then NST NST >= 1 then NST possible (red,
purple).possible (red, purple).
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ReferencesReferencesJack R.Jack R. Cooley. 1978: Cooley. 1978:
Cold Air Funnel Clouds.Cold Air Funnel Clouds. Monthly Weather
ReviewMonthly Weather Review: Vol. 106, No. 9, pp. 1368: Vol. 106,
No. 9, pp. 13681372. 1372. Burgess, D. W., and R. J. Donaldson,
1979: Contrasting tornadic storm types. Preprints, 11th Conf. on
Severe Local Storms, Kansas City, KS, Amer. Meteor. Soc.,
189192.Roger M.Roger M. Wakimoto and James W.Wakimoto and James W.
Wilson. 1989: Wilson. 1989: NonNon--supercell Tornadoes.supercell
Tornadoes. Monthly Weather ReviewMonthly Weather Review: Vol. 117,
: Vol. 117, No. 6, pp. 1113No. 6, pp. 11131140. 1140. Raymond
H.Raymond H. Brady and Edward J.Brady and Edward J. Szoke. 1989:
Szoke. 1989: A Case Study of Nonmesocyclone Tornado Development A
Case Study of Nonmesocyclone Tornado Development in Northeast
Colorado: Similarities to Waterspout Formation.in Northeast
Colorado: Similarities to Waterspout Formation. Monthly Weather
ReviewMonthly Weather Review: Vol. 117, No. 4, pp. : Vol. 117, No.
4, pp. 843843856. 856. Rita D.Rita D. Roberts and James W.Roberts
and James W. Wilson. 1995: Wilson. 1995: The Genesis of Three
Nonsupercell Tornadoes Observed The Genesis of Three Nonsupercell
Tornadoes Observed with Dualwith Dual--Doppler Radar.Doppler Radar.
Monthly Weather ReviewMonthly Weather Review: Vol. 123, No. 12, pp.
3408: Vol. 123, No. 12, pp. 34083436. 3436. Bruce D.Bruce D. Lee
and Robert B.Lee and Robert B. Wilhelmson. 1997: Wilhelmson. 1997:
The Numerical Simulation of NonThe Numerical Simulation of
Non--Supercell Supercell Tornadogenesis. Part I: Initiation and
Evolution of Pretornadic Tornadogenesis. Part I: Initiation and
Evolution of Pretornadic Misocyclone Circulations along a Dry
Misocyclone Circulations along a Dry Outflow Boundary.Outflow
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3260. 60. Bruce D.Bruce D. Lee and Robert B.Lee and Robert B.
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Tornadogenesis. Part II: Evolution of a Family of Tornadoes
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Vol. 54, No. 19, pp. 2387: Vol. 54, No. 19, pp. 23872415.2415.Bruce
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Wilhelmson. 2000: The Numerical Simulation of Nonsupercell The
Numerical Simulation of Nonsupercell Tornadogenesis. Part III:
Parameter Tests Investigating the RoleTornadogenesis. Part III:
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Vertical Shear.and Boundary Layer Vertical Shear. Journal of the
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No. 14, pp. 2246: Vol. 57, No. 14, pp. 22462261.2261.Jon M. Davies.
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Non-Supercell Tornadoes and the NST Parameter: Landspout
Tornadoes June 16 2004WFO La Crosse Research Series
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Summary2004 June 16: Environment2004 June 16: Environment2004 June
16: Environment18z 2004 June 16: Environment18z 2004 June 16:
Environment18z 2004 June 16: Environment18z 2004 June 16:
Environment18z 2004 June 16: Environment18z 2004 June 16:
Environment18z 2004 June 16: Environment18z 2004 June 16:
Environment18z 2004 June 16: EnvironmentRadar Loop 1722z-2051z
(fast)Radar Loop 1722z-1900z (slow)19z 2004 June 16: Environment19z
2004 June 16: Environment2004 June 16: Osage Cell 2004 June 16:
Osage Cell 2004 June 16: Osage Cell 2004 June 16: Osage Cell 2004
June 16: Osage Cell 2004 June 16: Osage Cell 2004 June 16: Summary
2004 June 16: Summary Situational AwarenessSituational Awareness18z
2004 June 16: NST Parameter19Z 30 March 2005: NST Parameter20Z 30
March 2005: NST Parameter21Z 30 March 2005: NST Parameter22Z 30
March 2005: NST Parameter30 March 2005: NST Parameter30 March 2005:
NST Parameter30 March 2005: NST Parameter5 April 2005: NST
Parameter5 April 2005: NST Parameter5 April 2005: NST Parameter5
April 2005: NST Parameter5 April 2005: NST Parameter19 April 2005:
NST Parameter19 April 2005: NST ParameterReferences